Biomolecules Test

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Biomolecules Test - 43

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Weekly Quiz Competition

Question 1
1 / -0

Which of the following statement is incorrect?

A
Amylose is water soluble component of starch

B
Amylopectin is water insoluble component of starch

C
$$\alpha$$-D Glucose units are present in amylose and amylopectin

D
None of these

Solution

Amylose is water soluble component which constitutes about 15-20% of starch.
Amylopectin is insoluble in water and constitutes about 80-85% of starch.
Both Amylose and Amylopectin have $$\alpha$$-D Glucose as their monomer units.
Question 2
1 / -0

How is the rate of enzyme catalysed reactions affected by 10$$^o$$C rise of temperature?

A
Doubles

B
Becomes four times

C
Halves

D
Remains unchanged

Solution

Most of the enzymes are protein molecules and extremes of temperature denature them. Optimum temperature range of enzymes is 20 to 30$$^o$$C in most cases. The velocity of an enzyme catalyzed reaction doubles with 10$$^o$$C rise in temperature. This is called as Q$$_{10}$$ value. Within limits of the optimum temperature range, the Q$$_{10}$$ value is 2-3.
So, the correct answer is option A.
Question 3
1 / -0

Which of the following principles is not true for zymogen activation?

A
Liberation of activation molecules

B
Hydrolysis of large, inactive precursors

C
Splitting off an inhibitor precursors

D
Conformational change brings certain amino acid residues together

Solution

The zymogen is inactive precursors of enzymes which undergo activation by proteolytic cleavage. It is cleaved to form the active enzyme. Many proteolytic enzymes (proteases) of the stomach and pancreas are regulated this way. Chymotrypsin and trypsin are initially synthesised as chymotrypsinogen and trypsinogen, respectively. Specific cleavage causes conformational changes that expose the enzyme active site. Because this type of activation is irreversible, other mechanisms are needed to inactivate these enzymes. Proteolytic enzymes are inactivated by inhibitor proteins that bind very tightly to the enzyme active site.
So, the correct answer is option D.
Question 4
1 / -0

Glycolysis occurs only in the presence of

A
Ca

B
Mn

C
Mg

D
Co

Solution

Reactions involving energy exchange through ATP are catalyzed by kinase enzymes. All the kinase enzymes require magnesium as their cofactor. In glycolysis hexokinase, pyruvate kinase, phosphoglyceric acid kinase all require magnesium as their cofactor.
Thus, the correct answer is option C.
Question 5
1 / -0

An example of disaccharide, made up of two units of the same monosaccharide, is:

A
maltose

B
sucrose

C
lactose

D
none

Solution

Diasaccharides are sugars or carbohydrates made by linking two monosaccharides.
sucrose $$=$$ glucose $$+$$ fructose.
maltose $$=$$ glucose $$+$$ glucose
lactose $$=$$ galactose $$+$$ glucose
Question 6
1 / -0

Which of the following statement is true for enzymes?

A
They lower the activation energy of a reaction by increasing the energy level of the substrate.

B
They lower the activation energy of a reaction by raising the energy level of the product.

C
They do not affect the free energy change between substrate and product.

D
They can be steroids instead of proteins at times.

Solution

Enzymes are biological catalysts which speed up biochemical reactions. According to the most widely accepted theory, enzymes bind to the substrate molecule and form a transition state. During the progress of a reaction the substrates are separated from products by an energy barrier which the substrates need to cross. This energy barrier is called as the activation energy. The activation energy barrier in case of transition state is far less as compared to the activation energy barrier in absence of enzymes. Hence, the rate of reaction is more in case of enzyme catalyzed reactions due to the formation of transition state and lower activation energy requirement. This change is brought about by an apparent increase in energy level of substrate molecules.
Question 7
1 / -0

Many of the actual sites of an enzyme contain metal ions that enhance reaction particularly by helping to bind the substrate or to withdraw electrons is called as

A
Coenzyme

B
Apoenzyme

C
Cofactor

D
All of the above

Solution

For some biochemical reactions a substance other than enzymes and substrate is required. These substances are called as coenzymes (organic compounds) or cofactors (inorganic ions like zinc and copper etc.). The coenzymes usually serve as an acceptor or donor of an atom or a group. Many coenzymes are derived from vitamins.
Question 8
1 / -0

Example of coenzyme is

A
CoA

B
NAD

C
FAD

D
All of the above

Solution

For some biochemical reactions, a substance other than enzymes and substrate is required. These substances are called as coenzymes or cofactors. The coenzymes usually serve as an acceptor or donor of an atom or a group, example - nicotinamide adenine dinucleotide (NAD) which is derived from vitamin niacin, flavin adenine dinucleotide (FAD) which is derived from vitamin riboflavin, Coenzyme A which is derived from pantothenate etc.
Question 9
1 / -0

Example of coenzyme is

A
Zn$$^{2+}$$

B
Lipase

C
Vitamin B

D
Lysine

Solution

For some biochemical reactions a substance other than enzymes and substrate is required. These substances are called coenzymes (organic compounds) or cofactors (inorganic ions like zinc and copper etc.). The coenzymes usually serve as an acceptor or donor of an atom or a group. Many coenzymes are derived from vitamins. B group of vitamins forma variety of coenzymes example Nicotinamide adenine dinucleotide (NAD) which is derived from vitamin niacin, Flavin adenine dinucleotide (FAD) which is derived from vitamin riboflavin, Coenzyme A which is derived from pantothenate, pyridoxal phosphate which is derived from pyridoxin, Thiamine pyrophosphate which is derived from thiamine etc.
Question 10
1 / -0

Cytochrome oxidase is an example of which of the following?

A
Exoenzyme

B
Endoenzyme

C
Coenzyme

D
Proenzyme

Solution

In mitochondrial electron transport system, complex IV also called as cytochrome oxidase, contains cytochrome a and a3. These cytochromes consist of two haeme groups bound to different regions of the same large protein that are therefore spectrally and functionally distinct. Cytochrome oxidase also contains two copper ions copper a and copper b that are crucial to the transfer of electrons to oxygen. This complex enzyme has evolved to carry out the four electron reduction of oxygen without generating the incompletely reduced intermediates such as hydrogen peroxide or hydroxyl free radicals which are very reactive species that would damage cellular components.

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Re-Attempt Weekly Quiz Competition

Biomolecules Test - 43

Result

Biomolecules Test - 43

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SHARING IS CARING

Question 1

Amylose is water soluble component of starch

Amylopectin is water insoluble component of starch

$$\alpha$$-D Glucose units are present in amylose and amylopectin

None of these

Solution

Question 2

Doubles

Becomes four times

Halves

Remains unchanged

Solution

Question 3

Liberation of activation molecules

Hydrolysis of large, inactive precursors

Splitting off an inhibitor precursors

Conformational change brings certain amino acid residues together

Solution

Question 4

Ca

Mn

Mg

Co

Solution

Question 5

maltose

sucrose

lactose

none

Solution

Question 6

They lower the activation energy of a reaction by increasing the energy level of the substrate.

They lower the activation energy of a reaction by raising the energy level of the product.

They do not affect the free energy change between substrate and product.

They can be steroids instead of proteins at times.

Solution

Question 7

Coenzyme

Apoenzyme

Cofactor

All of the above

Solution

Question 8

CoA

NAD

FAD

All of the above

Solution

Question 9

Zn$$^{2+}$$

Lipase

Vitamin B

Lysine

Solution

Question 10

Exoenzyme

Endoenzyme

Coenzyme

Proenzyme

Solution

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